This invention relates to a pavement marker intended to be mounted to a roadway surface and having improved visibility in daytime, as well as providing a visible signal at night.
Pavement markers have become widely accepted as means for providing visible signals which mark traffic lanes and control the flow of traffic on roadways in combination with, or in place of, conventional painted traffic lines. A large number of such markers employ retroreflectors which retroreflect light emanating from oncoming vehicles to provide a signal visible to the operators of such oncoming vehicles, especially at night.
Typically, pavement markers comprise a base member designed to be firmly secured to the associated roadway surface; and a retroreflective signal means mounted on or formed as part of the base member. As disclosed in basic U.S. Pat. No. 3,332,327, assigned to the assignee herein, the disclosure of which is incorporated herein by reference, the base member can be a molded plastic housing having cube corner elements. Some pavement markers are intended to be permanently installed on a roadway surface. These include those markers sold by the assignee herein under the model names Stimsonite Model 948, and Stimsonite Model 953. Pavement markers also can be used to delineate roadway construction work zones. Such markers include those sold by the assignee herein under the model name Stimsonite Model 66, intended for temporary installations at construction work zones. The Stimsonite Model 88 sun country marker also can be used for more permanent installations at construction work zones. Pavement markers of the prior art are also disclosed in U.S. Pat. Nos. 5,078,538 and 5,403,115, both assigned to the assignee herein and both being incorporated herein by reference. Other pavement markers of other manufacturers are also available.
In such markers of the prior art, the plastic housing of the pavement marker is typically an opaque color suitable for the intended use of the marker. For example, a marker intended to be placed on or in place of a white dividing lane may be a white plastic, a marker intended to be placed on or in place of a yellow dividing line may be yellow plastic, and a marker intended for temporary placement in a roadway construction work zone may be yellow or white.
While such markers are intended to provide enhanced nighttime visibility by retroreflecting light from vehicle headlights back to the vehicle drivers, it also would be desirable if the markers could provide enhanced daytime visibility. The upper and side surfaces of a raised pavement marker are not readily visible to a driver of an oncoming vehicle, because these surfaces are at an angle highly oblique to the driver""s viewing direction. Daytime visibility therefore must be provided primarily by the front surface of the marker, which is easily seen by the driver. The major portion of the marker front surface, however, is occupied by the retroreflector, which for optical reasons appears almost black in daytime. It would be desirable to provide a roadway marker mounted on a roadway surface that provides greater daytime visibility than those markers currently available or described in the prior art. In particular, it would be desirable to provide pavement markers having enhanced daytime visibility and adapted for use in roadway construction work zones.
In accordance with the invention, a pavement marker comprises a base member having a top portion and a bottom portion, the bottom portion having a bottom surface adapted to be secured to the pavement surface, the top portion having a smooth flat top surface, a smooth flat bottom surface substantially parallel to the top surface and at least one edge surface between said top surface and said bottom surface, the bottom surface of the top portion being secured to the bottom portion of the base member such that there is an air gap between at least part of the top portion and at least part of the bottom portion of the base member, the top portion of the base member being made of a transparent fluorescent resin material. It has been found that light received by the smooth flat top surface of the top portion of the base member is directed internally through the top portion and emitted from the edge surface of the top portion, thereby providing a surprisingly bright daytime signal to drivers of oncoming vehicles. Optionally, the bottom portion of the base member can also be a transparent fluorescent material, or it can be an opaque color of any choice. In a preferred embodiment, the pavement marker will also include a retroreflector mounted on the base member to provide nighttime visibility to drivers of oncoming vehicles. When the inventive marker is to be used in a roadway construction work zone environment, it is preferred that the top flat portion be of a transparent fluorescent orange, such as is commonly used in road signs to denote a construction work zone.